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Seminar: "Sensing molecules and forces with DNA origami"

Speaker

Prof. Tim Liedl, Physics, LMU Host: Omar Saleh

Date and Location

Wednesday February 24, 2016 11:00am to 12:00pm

1601 Elings

Abstract

We use the DNA origami method [1] for the fabrication of functional self-assembled nanoscopic objects and materials [2]. By offering attachment sites for active nano-components on these DNA objects, we have realized complex and nanometer-precise assemblies of fluorophores and plasmonic nanoparticles [3].

Currently we are exploring plasmonic nanoantennas made by DNA origami that can be used as reliable and efficient probes for surface enhanced Raman spectroscopy (SERS). The nanoantennae are built up by pairs of gold nanoparticles on DNA origami templates at separation distances between 9 nm and 4 nm in order to achieve plasmonic coupling and the formation of strong plasmonic ‘hot spots’ [4].

In recent, unpublished experiments we studied force interactions between biomolecules. Well-established techniques such as atomic force microscopy and magnetic or optical tweezers are usually applied to investigate protein folding or biopolymer – particularly DNA – elasticity. Here we present a nanoscopic DNA origami based single-molecule force spectroscopy device without any physical connection to a micrometer-sized bead or cantilever. We exploit the entropic elasticity of single-stranded DNA to apply tension on a system mounted on the device [5] and single-molecule Förster Resonance Energy Transfer (smFRET) is used as a readout to study two dynamic systems under different tensions: the transition behavior of a Holliday junction and the bending of a DNA promotor sequence induced by the TATA-binding protein (TBP). We are able to generate reliable single-molecule force spectroscopy data in the piconewton range in a high throughput fashion. Our DNA origami force spectrometer can in principle be employed with a wide variety of DNA interacting biomolecules.